Generally the electrostatic capacity of a film condenser is determined by the dielectric constant of the polymer used in making the film as well as the films thickness and area.
Usually, the highest dielectric constant of any polymer of an organic high molecular substance is on the order of about 5. Rarely some polymers of fluorine type compounds exhibit a dielectric constant of about 10. These polymers, however, have not been well accepted for actual use due to restrictions such as high cost and insufficient dielectric breakdown strength. Efforts are being made to decrease the thickness of films for the purpose of increasing the electrostatic capacity. The decrease of film thickness, however, is restricted by cost increases and impairment of the ease of work involved. In addition, the increase in the area of films is restricted by the outline dimensions of the condenser. A method for inexpensively improving the dielectric constant of a dielectric film has been in demand.